Congratulation to Di Tan for his article “Continuous
gradient nanoporous film enabled by delayed directional diffusion of solvent
and selective swelling” has been accepted by Langmuir.
Nature-inspired porous structures are highly
desired in the fields of new materials, sustainable energy, biological &
chemical science etc. Here, a new strategy for the fabrication of continuous,
gradient nanoporous polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) film is
established. The continuous nanopore gradient along the direction of film
thickness (~120 μm) is achieved via delayed directional diffusion of dynamic binary
solvent of ethanol/water and selective swelling of P2VP domains. Ethanol in
binary solvent diffuses into the film from one side to another, which is
retarded by the water gate as water is concentrated at the film surface. The
delayed diffusion matches the swelling rate of P2VP domains, forming the
continuous nanopore gradient normal to the film surface.
